Means for grinding small holed bushings



'Dec.3,194. J, KAPLAN 2,412,048

MEANS FOR GRINDING. SMALL-HOLED BUS'HINGS Filed Nov. 24, 1945 INQENTORJosey/2 [(6 BY 5 a ATTORNEY Patented Dec. 3, 1946 MEANS FOR GRINDINGSIHALL HOLED BUSHINGS Joseph Kaplan, Brooklyn, N. Y.

Application November 24, 1945, Serial No. 630,638

3 Claims.

This invention relates to new and useful improvements in a machine forthe grinding of small holed bushings or other parts where the outsideperiphery is to be concentric or in similar relation with the holes.

More specifically, the present invention proposes the construction of a,machine for grinding small parts such as bushings having a center boreof extremely small size, the small size of the bushings making itdifiicult if not impossible to handle same in conventional machines.

The new invention has particular application to the art of grinding tosize, extremely small bushings concentric with their holes. Using it, anextremely high degree of accuracy will be readily and consistentlyobtained, even where it is required to prepare very large numbers ofsmall bushings in rapid succession on one and the same machine,utilizing but a minimum amount of time for aligning, precision grindingand ejecting the bushings. It will readily be seen that the new methodand machine are extremely efficient in operation, yet eminently simplein design, easy to install, and relatively easy .to operate Withoutdifficulty even by unskilled operators lacking prolonged periods oftraining and instruction heretofore necessary for efficient operators inthis art. Many other advantages of the invention will readily appear tothose skilled in the art studying the teachings of the instantspecification.

A further object is to provide a machine for grinding small bushingsexteriorly concentric with their axial bores, said machine having astationary wire held taut between two chucks, the wire forming a supportfor the bushing to be ground.

For further comprehension of the invention, and of the objects andadvantages thereof, reference will be had to the appended claims inwhich the various novel features of the invention are more particularlyset forth.

In the accompanying drawing forming a material part of this disclosure-Fig. 1 is a front elevational view showing the machine of the presentinvention with the bushing to the ground in position for having themethod of the present invention performed thereon.

Fig. 2 is a plan view taken from above and showing the embodiment of theinvention shown in the preceding figure.

Fig. 3 is a perspective view of a bushing used and prepared inaccordance with this invention.

Fig. 4 is a perspective view in detail showing the keyed fitting whichholds and causes rotation of the bushing of Fig. 3.

Fig. 5 is an enlarged axial section through the fitting and bushing,which are in mating position.

Fig. 6 is a perspective view of the fitting and the correspondingholding part pictured in detail apart from the remainder of the machine.

The main principle of the present invention consists in having acentrally aligned stretched wire held firmly in between two chucks. Thewire acts as a stationary axis over which the bushing to be groundrotates, while it is being ground by a grinding wheel. The diameter ofthe wire should be preferably about one to several tenthousandths of aninch less in diameter than the bore in the bushing in order to get goodresults in the concentricity of the inside and outside diameters of thebushing.

The machine, according to this invention, comprises two parallelvertical standards l0 and H holding two stationary chucks l2 and 22respectively. The construction of the tail stock of a lathe will verywell suit the purposes of chuck 22 in adjusting the distance between thetwo chucks as needed. In the present instance chuck 22 is shown ashaving a stem 13 sliding in a bore in the standard I I, a set screw 28being employed for locking the chuck 22 in any adjusted position.

A fitting or auxiliary bushing l1, best shown in Fig. 4, is provided.Its function, as will presently appear, is to drive the bushing 26 (Fig.3) while it is being ground. The bushing l1 consists of a piece of roundstock of steel having a hole l9 drilled through the center and having atooth extending diametrically across one end. This tooth 20 is adaptedto fit loosely in a slot 21 formed in one end of the bushing 26. Bushing26 has an axial bore 25.

An electric motor 3| drives a pulley l4 mounted on the standard In bymean of a belt. A dog 2| is secured to the pulley and has a collarsurrounding the bushing l1 and secured thereto by a set screw 18. Thedog has two arms secured in holes in the pulley. Thus rotation of thepulley effects rotation of the dog and consequently rotation of theauxiliary bushing, the auxiliary bushing, when its tongue 20 is disposedin the slot 21 of the bushing to be ground, rotating this bushing.

In order to prepare the bushing 26 for external grinding, the bore 25must first be made and the slot 21 must be milled therein. After theexternal surface is ground, the end having the slot 21 may be ground toeliminate this slot.

The machine further comprises'a wire i which is first secured in thechuck I2. The auxiliary bushing I1 is then slid on the wire and into thecollar of the dog where it is secured by the set screw l8, the arms ofthe dog being inserted in the holes in the pulley. Then the bushing 26to be ground is slid on the wire, the tooth 20 and slot 2'! beingadjacent each other and interfitting. The end of the Wire I6 is thengripped in the chuck 22 which is then adjusted longitudinally to givethe correct distance between the faces of the two chucks and theadjacent faces of the bushings. This distance is preferably only a fewthousandths of an inch, but is shown larger in the drawing for clarity.That is to'say, the

bushings, When interfitted, do not entirely fill the space between thechucks but some clearance is permitted to allow the bushings to rotateunhampered.

A grinding wheel 29, mounted on a shaft .39, is shown fragmentally inFigs. 1 and 2. This wheel is rotated by another motor, in a well knownmanner, to grind the bushing 26. The wheel 29 will be mounted forlongitudinal movement along the bushing 28. As grinding wheels of thistype are well known, no further description or showing thereof is deemednecessary.

In order to grind the bush-ing 2B, the motor 3| is started and thus thebushing 26 rotates. At the same time the grinding wheel 29 is started.The wheel 29 is moved back and forth along the bushing 2-6 until theexterior surface of the bushing has been ground the desired amount.After the outside diameter of the bushing is finshed to size, the chuck22 is opened and the bushing 28 removed and a new one inserted on thewire I'B, whereupon the operation is repeated.

While I haveillustrated and described the preferred embodiments of myinvention, it is to be understood that I do not limit myself to theprecise constructions herein disclosed and the right is reserved to allchanges and modifications coming within the scope of the invention asdefined in the appended claims.

Having thus described my invention, what I claim as new, and desire tosecure by United States Letters Patent is:

1. In a machine for grinding a bushing or the like having a centralbore, two spaced chucks, a

wire or rod secured at its ends therein, an auxiliary bushing mounted onsaid wire or rod said bushing to be ground being adapted to be mountedon said wire or rod next to said auxiliary bushing, said auxiliarybushing having means for locking with said bushing for rotating the samewhen said auxiliary bushing is rotated, and means for rotating saidauxiliary bushing.

2. A machine for grinding a bushing or the like having a central boreand a diametral slot in its end comprising two spaced standards, apulley mounted on one of said standards for rotation, a chuck-secured tosaid standard, an electric motor for driving said pulley, a chuck adustably secured to said other standard, a wire or rod secured at itsends in said chucks, an auxiliary bushing freely supported on said wireor rod, a

dog .secured to said auxiliary bushing and to said pulley for rotatingsaid auxiliary bushing, said auxiliary bushing having a diametral tonguein one of its ends for interfitting with said slot in said bushing to beground, said bushing to be ground being adapted to be freely supportedon said wire or rod, and rotatable grinding means for grinding theexterior surface of said bushing to be ground.

3. A machine for grinding a bushing having an axial bore and adiametrical slot in one end comprising two spaced standards, a chuckrigidly secured to one of said standards, a chuck adjust: .ably securedto the other of said standards, a pulley rotatably mounted on the firstof said standards, means for rotating'said pulley, a wire or rod securedat its ends in said chucks, a fitting rotatably mounted on said wire orrod having a diametrical tongue on one end for interfitting with saidslot when said bushing is mounted on, said wire or rod, a dog connectingsaid fitting and pulley for rotation of said bushing, said dog havingtwo legs secured in holes in said pulley and a' collar surrounding saidfitting and provided with a set screw for firmly locking said collar andfitting and rotatable grinding means for grinding the exterior surfaceof said bushing to be ground. V

JOSEPH KAPLAN.

